Fantastic stuff! Great interplay between gameplay and story, solid mechanics, and fun shooting! For a jam game, it's a really good effort. The environments and the ships could maybe have had the same (or similar) pixel size, but one uses what one can. :) I did not quite manage to finish it, as after killing the big spinny boss thing at the end, I always get killed by the constantly-spawning enemy ships before I can...make my escape? Not sure what I should do. I also noticed that the shop seems to be randomized every week, meaning I can't e.g. save up for a medium shield or something, I just have to hope there's something I can afford there when I get there.
The biggest gripe I have is actually click-to-shoot. I understand you have the secondary attack attached as a charge-up when you hold down the mouse button, but this is the kind of game where you will literally always want to be shooting. I would suggest making the cannons fire when you hold down the mouse button (or space), and move the charge-up of the special attack to another button - like mouse 2, or F, or something :)
Anyway, great job!